More than 1/2 our user base has not been able to get into our ZOHO desk app today. This morning out of nowhere users are getting the following error:

{"result":"failure","cause":"Invalid APIKey"}

I already put a ticket in this morning at around 8:30-9:00 and have not had a response, ETA, or any other type of information. What is the cause of this error? Nothing has changed on our end and it was working fine the previous day.